[Kon5ole]

Better reactor designs that can’t basically self-combust through accidents or operational errors are an improvement of course, but I’m not aware of any design that eliminates the need to produce relatively large quantities of waste. That in itself poses a large risk.

[fighterpilot]

Ok but what is the tail risk here. Can you outline a series of causal steps where a molten salt reactor will cause more than 100,000 to 500,000 deaths? If you're just saying that perhaps maybe there will be 2,000 deaths, well that's still an incredible safety profile compared to the number of deaths caused by other energy sources.

[Kon5ole]

Sure - Creating the fuel for molten salt reactors requires a series of steps where highly radioactive materials will have to be handled, stored, transported and controlled by humans.

As shown with the examples given earlier (which are just a few of many), such situations will inevitably provide opportunity for the materials to be lost or stolen. (IAEA has documented 18 cases of stolen radioactive elements from various sites that handle radioactive materials).

One of the elements needed for molten salt reactor fuels is plutonium. 500 grams of plutonium is estimated to be enough to kill up to 2 million people by conservative estimates.

Presumably you will need more than 500 grams regularly to run a salt reactor, so any number of malicious methods can kill 100 000 to 500 000 people, if someone gets their hands on even small amounts of plutonium.

I think that when people reach the conclusion that the benefits of nuclear outweigh the downsides it is usually because they haven't really considered the real downsides fully. The benefits are huge, to be sure, and tempting.

Now that being said - if a reactor design appears that would significantly /reduce/ the amount of dangerous materials that have already been created, and not require any more of it to be created, I think it would be a good idea to build such a reactor to get rid of the waste we already have.

Speaking of molten salt, I find it more interesting as a concept for energy storage. Solar power can superheat salt and use it to genereate energy even at night. A solar power plant in Spain has generated electricity continously (day and night) for over a month using this technology.

https://cleantechnica.com/2013/10/14/worlds-largest-solar-th...

I believe that we have an abundance of very promising - sometimes already proven - technologies that will let us generate stable electricity from intermittent, clean sources with comparatively insignificant risk to human lives.